How do we know that the gospel is sufficient for salvation?

The sufficiency of the gospel rests on the truth that salvation is a gift from God, fully accomplished by the life, death, and resurrection of Jesus Christ. Galatians 3:13 highlights that Christ has redeemed us from the curse of the law, showing that any attempt to add works to grace nullifies the gospel (Galatians 5:4). Preaching the gospel emphasizes that faith, not human effort, is the evidence of life for the believer. It is through faith in Christ that we receive the promise of eternal life, which reinforces that all who call upon the name of the Lord will be saved (Romans 10:13). Thus, the power of salvation lies exclusively in the message of Christ crucified, underscored by His atoning work.